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"Highly stressed rock in stopes continues to be a primary safety risk for miners in underground mines because this condition can result in failures of ground that lead to both injuries and death. Personnel from the Spokane Research Laboratory of the National Institute for Occupational Safety and Health studied two methods for identifying stress in rock. A seismic tomographic survey, finite-difference analysis, laboratory measurements of compression wave (ultrasonic) velocities in rock cores, and site geology were integrated to evaluate the use of seismic tomography for identifying induced pressures in an underground pillar at the Edgar Mine, Idaho Springs, Colorado. Electromagnetic (EM) emissions were also investigated in the Galena Mine, a deep underground mine in Idaho, in an effort to determine if these emissions could be used as indicators of impending catastrophic ground failure. Results of this research indicated that (1) seismic tomography appears to be a useful tool for determining relative stress in underground pillars, while (2) EM emissions do not appear to be significant precursors of impending catastrophic ground failure." - NIOSHTIC-2

Three-dimensional time-lapse velocity tomograms were generated to image stress redistribution around a longwall panel to produce a better understanding of the mechanisms that lead to ground failure. Mining-induced microseismic events provided passive...

Three-dimensional velocity tomograms were generated to image the stress redistribution around an underground coal longwall panel to produce a better understanding of the mechanisms that lead to ground failure, especially rockbursts. Mining-induced mi...

Highly stressed rock in stopes continues to be a primary safety risk for miners in underground mines because it can result in failures of ground that lead to both injuries and death. Spokane Research Laboratory personnel investigated electromagnetic ...

"The solubility of anhydrous aluminum chloride in solutions of titanium tetrachloride and vanadium tetrachloride was determined as part of a research project by the Bureau of Mines to make a homogeneous alloy sponge of titanium, vanadium, and aluminu...